Brocade BigIron RX Series Configuration Guide - Manual (Page 427)

BigIron RX Series Configuration Guide 349
53-1002484-04
SuperSpan™
12
Note that when VLAN 1 is not the default VLAN, the ports must have an untagged VLAN enabled in
order to process IEEE 802.1Q BPDUs.
For example, the following configuration is incorrect.
BigIron RX(config)# default-vlan-id 1000
BigIron RX(config)# vlan 1
BigIron RX(config-vlan-1)# tagged ethernet 1/1 to 1/2
BigIron RX(config-vlan-1)# exit
BigIron RX(config)# interface ethernet 1/1
BigIron RX(config-if-e10000-1/1)# pvst-mode
BigIron RX(config-if-e10000-1/1)# exit
BigIron RX(config)# interface ethernet 1/2
BigIron RX(config-if-e10000-1/2)# pvst-mode
BigIron RX(config-if-e10000-1/2)# exit
In the configuration above, all PVST BPDUs associated with VLAN 1 would be discarded. Since IEEE
BPDUs associated with VLAN 1 are untagged, they are discarded because the ports in VLAN 1 are
tagged. Effectively, the BPDUs are never processed by the Spanning Tree Protocol. STP assumes
that there is no better bridge on the network and sets the ports to FORWARDING. This could cause
a Layer 2 loop.
The following configuration is correct.
BigIron RX(config)# default-vlan-id 1000
BigIron RX(config)# vlan 1
BigIron RX(config-vlan-1)# tagged ethernet 1/1 to 1/2
BigIron RX(config-vlan-1)# exit
BigIron RX(config)# interface ethernet 1/1
BigIron RX(config-if-e10000-1/1)# pvst-mode
BigIron RX(config-if-e10000-1/1)# exit
BigIron RX(config)# interface ethernet 1/2
BigIron RX(config-if-e10000-1/2)# pvst-mode
BigIron RX(config-if-e10000-1/2)# exit
Setting the ports as dual-mode ensures that the untagged IEEE 802.1Q BPDUs reach the VLAN 1
instance.
SuperSpan™
SuperSpan is an Brocade STP enhancement that allows Service Providers (SPs) to use STP in both
SP networks and customer networks. The SP devices are Brocade devices and are configured to
tunnel each customers' STP BPDUs through the SP. From the customer's perspective, the SP
network is a loop-free non-blocking device or network. The SP network behaves like a hub in the
sense that the necessary blocking occurs in the customer network, not in the SP.
The Brocade interfaces that connect the SP to a customer's network are configured as SuperSpan
boundary interfaces. Each SuperSpan boundary interface is configured with a customer ID, to
uniquely identify the customer's network within SuperSpan.
Figure 34 shows an example SuperSpan implementation. In this example, an SP's network is
connected to multiple customers. Each customer network is running its own instance of standard
STP. The Brocade devices in the SP are running SuperSpan.
FIGURE 34 SuperSpan example